Temperature control device



July 5, 1938. 1.. L. YOUNG TEMPERATURE CONTROL DEVICE I Filed July 10, 1955 INVENTOR LLOYQ LXOUNG BY %ZMM ATTORNEY Patented July 5, 1938 PATENT OFFICE TEMPERATURE CONTROL DEVICE Lloyd L. Young, Patchogue, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application July 10,

4 Claims.

This invention relates to a temperature control device or switch, and is particularly adapted for opening and closing an electrical circuit which controls a heater current.

- An object of this invention is to simplify and improve fluid-expanding temperature control devices or switches of the mercury type which can be applied to radio apparatus or any other device requiring substantially constant temperl0 ature.

The fundamental principles of this improved temperature control device or switch are based upon the Bourdon pressure gauge.

In the devices known in the prior art there has 15 not been sufficient sensitivity and mechanical ruggedness to satisfactorily apply them to commercial radio apparatus generally as the insensitivity of a thermo-regulator prevents the main tenance of an exact even temperature. Furthermore, mechanical fragility renders such instruments unsatisfactory for use by an unskilled operator.

It is an object of this invention to overcome these defects of the devices or switches known in the prior art and to combine high sensitivity with a device having rugged mechanical strength.

This invention is also an improvement over the temperature control system of the mercury contact-making device which has been described in my copending application Serial No. 568,962, filed October 15, 1931.

This invention will be more thoroughly understood by referring to the accompanying drawing, in which Fig. 1 is a plan view of the temperature control device of this invention;

Fig. 2 is a side elevation of Fig. 1, and is partly in section; and

Fig. 3 is a detail of the thin metallic tube eiekw ment.

Referring now to Figs. 1 and 2, a central support tube I is threaded into the heater block or casing 8 which may be a part of any desired apparatus, the temperature of which is to be controlled. Contained within the block 8 is an expansible liquid, such as oil, acetone, alcohol, carbon tetrachloride, glycerine, or any other suitable liquid having the requisite expansion qualities.

Located about midway on the central support 50 I there is a short tube 9 which supports and con nects, in fluid communication, the pressure gauge element 3 with the central support tube I. A detailed showing of this pressure gauge element is shown by Fig. 3. The tube is made of very thin 5 brass or copper which is pressed flat and then all 1935, Serial No. 30,670

bent into an arc of a circle of any suitable radius, as shown in Fig. 1. A small opening is made on one side near the end facing the short tube 9, the pressure element 3 being soldered in any suitable manner, such as by silver solder to the short tube 9 so that the spacing inside the pressure element 3 is in fluid communication with the chamber I I. Both ends of element 3 are sealed so as to be perfectly oil-tight. The unsupported end It is connected by means of an electrically insulated pin I to one end of a lever 5 which forms a linkage sys tem between the pressure tube and the electrical contacts. The lever 5 is arranged in such a manner that movement of pressure element 3 will not be clamped by the stiffness of the points of connection through pin I. Therefore, mechanical connection will always be such that any movement of the element 3 will be communicated to lever 5 so that lever 5 will be arranged to freely move about pin I2 which acts as a pivot point for the lever system.

The movement of lever 5 will cause an electrical contact to be made or broken at the contact 6 which is secured to an insulated ring 4 and fastened to the central support member I by means of a threaded stud I! and further insulated by a Washer 53, as shown in Fig. 1.

The top of the central support tube I contains an adjustable needle valve 2 which shuts off the middle chamber inside the element 3 and the support tube I from atmosphere entering through the aperture or opening 22, or by space between the threads. The heating element I5 is located within the heater block 8 and is connected to a control circuit 20 which comprises any suitable relay device such as the well-known Thyratron relay, not shown in detail.

A protective housing it is desirable to protect the control device and the electrical contacts. A thermometer I I indicates the temperature of the heating block 8.

The operation of the device is as follows:

Assuming that the complete unit is at room temperature and that the desired operating temperature is to be 45 centigrade, the needle valve 2 is first opened and no pressure will be built up in chamber II so the contact device will be inoperable.

When the temperature has risen to the desired value, as indicated by the thermometer 2| which is intimately connected with the block 8, the operator closes tightly the needle valve 2 and the device will then start regulation of the temperature. The generation of heat in the heating element I5, located within the oil-filled block 8,

causes the oil to expand and the pressure element 3 to function in the same manner as the element of a Bourdon pressure gauge, that is, the free end flexes outward and this motion is transmitted through pin 1 to the linkage system 5 which is pivoted about a point 12, thus making contact with contact element 6. Through the terminal leads l3 and M the heating relay 2!) is short-circuited and the heating current in the heating element I5 is interrupted. When the oil begins to cool and contract, the pressure inside element 3 drops and the free end flexes inwardly causing the contact 6 to break, thus reestablishing the heating current.

This cycle of operation is repeated in very short time periods, which provides a substantially constant temperature regulation of the block 8. The Bourdon tube will be made to operate at the low pressure end of its pressure range so as to stand considerable overheating without harmful pressure.

While only one modification of this invention has been disclosed, it is to be distinctly understood that other modifications will present themselves to those skilled in the art. For example, lever 5 may be eliminated and the contact made directly in the free end of element 3. It is to be further understood that this invention is not to be limited to the modification as shown, except such limitations as are clearly imposed by the appended claims.

Having thus described my invention, what I claim is:

l. A temperature control switch for regulating the temperature of a heating unit located within a casing containing a fluid, said switch comprising a central support tube located above said cas ing and in fluid communication therewith, an opening in the side of said central support tube, an insulating ring surrounding said central support tube, a pressure gauge of the Bourdon tube type partly surrounding said insulating ring and in fluid communication with the opening in said support tube, a linkage system secured to said insulated ring and arranged to operate electrical contacts for regulating the heating unit located within said casing.

2. A temperature control switch for controlling the temperature of a heating unit located within a casing containing a fluid, said switch comprising a central support tube located above said casing and in fluid communication therewith, an opening in the side of said support tube, an insulating ring surrounding said central support tube, a pressure gauge of the Bourdon tube type, an electrical contact secured to said insulating ring and a linkage system pivotally located on said insulating ring and cooperating with said pressure gauge which is in fluid communication with the opening in said central support tube, said pressure gauge linkage system and contact device arranged for controlling the temperature of said heating unit.

3. A temperature control switch for regulating the temperature of a casing containing a fluid, said switch comprising a central support tube located above said casing and in fluid communication therewith, an adjustable needle valve in fluid communication with the outside atmosphere for adjusting the temperature to be regulated within said casing, an insulating ring surrounding said central support tube, a pressure gauge of the Bourdon tube type partly surrounding said insulating ring, a linkage system arranged to operate electrical contacts for controlling a heating unit located within said casing.

4. A temperature control switch for controlling a heating unit located within a casing containing a fluid, said switch comprising a central support tube located above said casing and in fluid communication therewith, an adjustable needle valve in fluid communication with the outside atmosphere for adjusting the temperature to be regulated within said casing, an opening in the side of said central support tube, a fluid pressure element adjacent said central support tube, a support element connecting said opening with said pressure, element, a lever system attached to said central support element cooperating with said pressure element to control the heating unit within said casing.

LLOYD L. YOUNG. 

